Patch "ALSA: pcm: prevent UAF in snd_pcm_info" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

ALSA: pcm: prevent UAF in snd_pcm_info

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
alsa-pcm-prevent-uaf-in-snd_pcm_info.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Robb Glasser <[email protected]>
Date: Tue, 5 Dec 2017 09:16:55 -0800
Subject: ALSA: pcm: prevent UAF in snd_pcm_info

From: Robb Glasser <[email protected]>

commit 362bca57f5d78220f8b5907b875961af9436e229 upstream.

When the device descriptor is closed, the substream->runtime pointer is freed. But another thread may be in the ioctl handler, case SNDRV_CTL_IOCTL_PCM_INFO. This case calls snd_pcm_info_user() which calls snd_pcm_info() which accesses the now freed substream->runtime.

Note: this fixes CVE-2017-0861

---
 sound/core/pcm.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -153,7 +153,9 @@ static int snd_pcm_control_ioctl(struct
 				err = -ENXIO;
 				goto _error;
 			}
+			mutex_lock(&pcm->open_mutex);
 			err = snd_pcm_info_user(substream, info);
+			mutex_unlock(&pcm->open_mutex);
 		_error:
 			mutex_unlock(&register_mutex);
 			return err;

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/alsa-pcm-prevent-uaf-in-snd_pcm_info.patch